Slide rule



Sept. 15, 1925.

J. S. WOLLK SLIDE RULE original Filed June 10. 1924 pag.3. P@

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9 lmlm Hl In] \1 .8, JS s mm uvankoz mllmll E555* Joseph 5. WoHk.

6 mm vHm *fr l l u f ma Fai-.tenten Eiept. i5, lgen arditi? Wil? and s si i i' SLDE RULE.

Application filed June 10, 1324-, Serial No. 719,267. 'Renewed August1l, 1925.

To all 107mm it may concern.'

Be it known that l", il snrni S, idioten, a citizen of the United Statesoit America, residing at New York, in the county ot New York and Stateot New York, have invented certain new and useful improvements in SlideRules, ot which the following is a specification.

This invention relates to an improvement in slide rules, and morepartieulaii'ly to a bridge therefor, in the use ot which the usualpositive readings ot the slide rule may be increased by at least twoliinn'es oit positive reading; that is to say, the unknown and unexpr edhair-line indication beyond the :final i if eated division of the sliderule may be positively expressed in one or two additional figures, thatis, to one or two additional places in the terms ot the slide rulereading.

In the use ot a slide rule with the ordinary bridge, the hair line inits indication for 'final reading is usually between two ot the linerline divisions on the slide rule, and the reading beyond the final linedivision ot the slide rule is ordinarily ignored. As this unknownmeasurement is a material part ot the true result, it 'follows that itthis usually unknown measurement can be positively vXpressed in figuresot the slide rule measurement, the linal result is that much nearer thetrue result, and hence the effectiveness of the slide rule is materiallyinereased.

rlhe bridge of the present invention is made of two independent sectionsarranged for limited relative movement and each Carrying' a vernierscale member ot ,tine line divisions. This bridge is used as an entiretyas is the ordinary bridge in setting; the hair iine for the properreading. When the bridge is used as an ordinary bridge, the respectiveVernier scale members have a particular point, say the Zero point oneach, in coincidence. l reading the final number on the slide rule, itwill be found lor example, that the hair line is beyond one of the finerline divisions, thereby expressing a result which is greater than thatindicated by the adjacent line division of the slide rule in thedirection ot reading. Und-er these conditions that seetion or theimproved slide, which carri-s the hair line, is movedback to the linalline line division ot the slide rule whieli indicates the final iieureot the readina with the slide rule under ordinary conditions. As theVernier on the section of the bridge whieh has not been moved stillremains in the position determined by the bridge, in its initialapplication 'for slide rule reading', this movenie-nt ot the hair linesection et the bri lne will cause a movement oi? the vernier Carried bysuch section latorally ot the vernier carried by the section remainingiized, and the relative reading on the two verniers n'ill indicate themeasurement in ver-nier reading' oi? this unknown measurement on theslide rule. This may be expr sed as ligure, say tor example, 5. rihe brie as an entirety then adjusted and operated to determine the distance onthe ,'einier reading@ b'` 'een the two slide rule line reaeinen,lbeter-er. ivliieh the hair line origxinaily indicated an unknownmeasurement. This is aerei .shed by adjustn es an ei wi th the Zero ,yto cause the rule divisioi'is, and tiei the seetion ot the ci. f] i mela rule earryiim; the ll i is moved indei eudently ot the other .zestiento eause ch hair line to coincide with the other line sion oit' theslide rule. The vernier then resses, in vernier reading, the distancebetween these two line divisions ot the slide rule. Consider this ,torexample to be indicated on the vernier reading?,` as 25. Thisn'ieasurement then, tor example, expresses the tull measurement ot tenuniform divisions between the two line divisions on the slide rulebeing` Considered. It the readingr1 Q5 on the vernier equals tendivisions of slide rule measurement between the lines of division on theslide rule, each of said ten divisions would equal a reading` of two anda half on the Vernier. As the unlmown measurement previously determinedshows a reading` oi 5 on the Vernier, and each of the ten divisionbetween the fine division lines on the slide rule equal two and a halfon the vernier, the unknown measurement obviously equals 2 on the sliderule. lli the vernier reading is 7, 'for example, .in the measurement otthe unknown slide rule reading, the second Vure ot the unknown reading'is easily detern'iined. rlhe above is a general .statement et theIoperation which will be nio-re speciilically deseril d hereinafter indirect relation to the accon'ipanying?,` drawi ugs.

The iniproved bridge tui-ther contemplates details oi" construction bywhich the bridge sections are initially held in absolute positionrelative to the slide rule, and such sections are lifted against otherthanr predeterinined liniit ot relative nioven'ient; t respectivevernici' scales having' direct and reverse readings, and each slidesection having1 a hair line 'for convenience in the use oit the bridgeat the. respective ends ot the slide rule.

The invention is illustrated in the acconipanying; drawings, in which:

Fig. l is a plan view showing; proved bridge applied to a slide rule.

2, 3, and 4?-, are similar views showing;` the relative positions oi?the bridge in deterininii'ig` actual measurements et the usual unknownmeasurement oit the slide rule.

Fie'. 5 .is a bottoni plan ot the bridf The bridge is inade in twosections il and B, each having` the yinereinal edgre porti i l toslidably cooperate with the slide rule. For a purpos` which will laterappear, each oit the sections A and I3 is provided with a hair line 2,and each. section turthcr vided with a Vernier scale. The. veruier scale8 oi? the section A. is secured in a cut out portion lot the inner edgeot such section, the opposin section B having` its inner edge out ont at5 to receive the end ot 'the vernier scale 3 when the bridge sectionsare in normal or initially operative positions. The bridggje section Bhas a verniei.' scale 6 set into a cut out portion ..7 oi the inner edgeot this section and fitting); into a out out portion S et the inner edgeot section A when the sections are together. The ve nier scales 3 and 6are divided with lines ot division, each having' a :fiero point, and oneot' said scales, as 3, having` the nialier divisions successivelynumbered, while the other such scale, as G, bea s numbers indicating'the Ininor divisions. lThese scales have their adjacent inare'ins incontact so that the readings may be readily effected,

As stated, each bridge section .has a hair line, and these hair linesare arranged adliacent the relatively outer edges of the sections, sothat the appropriate hair line niay be used when the bridge has beenadjusted near the end of the slide rule, to avoid carrying' the othersection over beyond the end oil the slide rule. These hair lines arefurther the ini`- arranged adjacent the outer edges ot the sections, sothat when the lines coincide with the tinal divisions on the slide rule,the ei:- treine outer edge or the bridge section will be inwardly of theadjacent free end ot the slide rnle, thus pern'iitting` convenientadjustment or the slide sections ot the 1 '1l\ rule withoutinterteriire` with the bridge.

is either bridge section may be used in determining),l slide rulenieasiufen'ient, it i.; i p parent that the vernici-s 3 and (S shouldhave reverse measurements so as to be used 'lo-r either end, and hencesaid vernicrs are shown as oit double relatively reversed scalemeasurements, as clearly indicated in l.. Furthermore, the` relativesprcailing;l nieve-- nient of the respective slide sections t belin'iited accurately in vernier adjustment, and for this result, aprojection 9 is provided on one oit the verniers as (3, which projectsinto a recess l() on the underside ot the other Vernier, as 3. Then thisprojection 9 engages one end oi the recess, the zero marks ot' the.verniers are in registry and the verniers are in nornial relation withthe bridge sections in contact ttor norinal use. The opposite wall otprojection 9 is threaded to receive a set screw ll, which may be a ljuste-d therein to engaoje the projection 9 in the opening` or relativeinovernent or the bridge sections, limiting this inoveinent as desired.

It is liurther necessary to maintain lute disposition of the hair linesat anp-les to the slide rule, and as the vernici' scales extend intorecesses in the bridge sections, any accumulation ot dust or dirt insuch recesses would interfere with the proper relative posit-ions of thebridge tions and might possibly change the posi tion ot the hair linesand interiore `with the proper slide rule reading. To avoid this, therecesses receivingv the Atree ends ot' the rei niers are cutI somewhatlarig'er than necessary, and the end marginal edgres oi" the bridgesections have rounded projections l? adapted to Contact in the uornialpositions ott the sections A. and B. Thus the point et contact istangential. to the sections, and hence absolutely accurate in theirrelative positions, while the comparatively enlarged recesses 'for thevernier scale sections prevent any accumulation oi? dust or dirt atthese points.

In the use ot the improved bridge. relier ence is had Larticular-ly toFigs. l, il and 4t. Note troin Fig. l, that the hair line 2 et thesection A indicates on the slide rule a inain division numbered sevenand the third ininor division thoreatter, which would be ordinarily readand will be hereinafter referred to as l., and such hair line is beyondthe third division ot the slide rule, showing an unknown 1neasurcment inexcess ot the 3. In this position oi llo fio

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the bridge, the Zero marks of the Verniers are in coincidence. Sectionik with the hair line is then n'ioved until suoli hair line registerswith the il division line on the slide rule, that is, with the lineimmediately adjacent the ha line and indicating the last ijiositivereading on the slide rnle, as shown in F 2. Vfith the section A adjustedso that the hair line is in coincidence with this final indicating lineon the slide rule, the section ll of the bridge meanwhile remaining inits original position, it is apparent that the respective Verniers aremoved relatively, and that the reading now expressed on these Verniersindicates in Vernier reading the unknown measurement on the slide ruleas the bridge was originally igiositioned. for example that the Vernierreading after this adjustment is 5. lt is now necessary to determine theVernier reading for the distance between the two slide rule divisionlines in which the hair line in its original placement was located. Thisis accomplished in the following way. rlhe bridge sections are movedtogether in normal relation, that. is, with the Zero marks on theVerniers in coincidence and the hair line 2 of section A is firstaligned with the division on the slide rule immediately beyond thatoccupied by the hair line in its original position as shown in Fig. 3,that` is to say, the line indicated at 13. lWith section B of the bridgenow held fixed, section il. is moved to coincide the hair line 2 thereofwith the slide rule division line on the opposite side of that positionof the hair line in its original application, that is, the line marked14;, as shown in Fig. 4. The Vernier then accurately7 expresses inVernier reading the distance between the lines 13 and 1&1, a portion ofwhich distance is the unknown reading of the slide rule in theorigii'ial position of the bridge, as indicated in Fig. 1. Assume forexample that the Vernier reading of the distance between the lines 13and 14 on the slide rule is lf' it is desired to express the unknowndistance on the slide rule, in .figures indicating a number of tenths orten divisions between the lines 13 and 14, it Vwill be apparent that thereading 25 on the Vernier .indicates ten such divisions, that is, onesuch division will indicate a reading of two and a half on the Vernier.The unknown distance measurement on the slide rule has been found tocorrespond to a reading of 5 on the Vernier, that is, two tenths of thedistance between the slide rule scale lines 13 and l-i. Therefore, theunknown reading on the slide rule is expressed by 2, which of courseconstitutes the next figure in the slide rnle reading beyond thosepositively determined by the slide rul-e indications.7 If, for example,the unknown reading was 7 on the Vernier, it is merely a matter ofmechanical computation to .find the second Y are of the unknown reading.

'lhns the improved bridge provides a simple `convenient means by whichthe usual slide rule reading is j iositively increased at least twoiigiii-es beyond that possible with the ordinary bridge. IObviousl,either hair line may be used and either section become the manipulatingsection for determining the measurements. rlhe duplication of hair linesis for convenience in using the bridge adjacent the respective ends ofthe sliden rule without the necessity of extending the bridge so farbeyond the end of such rule as to permit one or the other of thesections to leave the slide rule.

The bridge may be constructed of any usual or preferred material, and ifdesired, and as contemplated, the bridge may be provided with amagnifying section overlying the Vernier and hair lines for accuracy inreading, this magnifying section not being illustrated as it is quitecommon in use with slide rule bridges.

The scales indicated at 3 and 6 and herein referred to as Vernicrs, aremerely tine line divisions having relation one to the other buthaving noVernier relation, as such is commonly understood to the divisions on theslide rule. rlhe purpose of these so-called Vernier scales is first todetermine, according to the Vernier scales. the unknown reading of theslide rule and then t-o determine the full reading on the slide rule ofthe distance between the two scale marks on the slide rule, betweenwhich the unknown reading occurs, and to determine the proportion of theunknown reading to the whole distance between such scale lines.

l1] hat l claim is:

1. A slide rule bridge made up of sec-- tions having a limited relativemovement., each section having a Vernier scale arranged for cooperativereading.

2. A bridge for slide rules, comprising independent sections, eachhaving a Vernier scale, means for limiting` the relative movement or"the sections, and a hair line provided on each section.

3. A bridge for slide rulesn comprising independent sections, a hairline carried by one of the sections, cooperating` Vernier scales carriedby the respective sections, and rounded meeting points of contact forthe sections when the latter are arranged in normal bridge formingrelation.

l. A slide rule bridge, comprising two sections, a Vernier' scalecarried by each of the respective sections, the scales being arranged toremain in edge contact for cooperative reading in the adjustment of thesections, and means to limit the relative movement of the sections to adistance substantially equalling that of the maximum Space between sh derule.

any two dwfslons on the coope'a'tng vel-nier marinus when the Miter arearranged 'in mmnul ln'dge i'i'n'mng rolaton, the zel-0 n'lzu'ks O' thevxfnier szlles being in c0- ncdcucc when sad mo'ftug ponts (ff contactam in en 'agennt En cs'mony whew! "l

